The present invention relates to a silicone anchorage additives and to their use in curable silicone coatings. More particularly, the present invention is related to alkoxy containing alkenyl functional organopolysiloxanes and to their use in curable silicone coatings.
Alkoxy containing polyorganosiloxanes have been described in the art. For example, Brown et al. in U.S. Pat. No. 3,122,522 discloses a siloxane compound wherein each molecule consists essentially of (1) at least two units of the formula [R'(OCH.sub.2 CH.sub.2).sub.c O].sub.a R.sub.b SiZR.sub.2 SiO.sub.0.5 and (2) units of the formula R.sub.d SiO.sub.4-d/2 in which each R and R' is independently selected from the group consisting of monovalent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals, each a has a value ranging from 2 to 3, each b has a value ranging from 0 to 1 in the sum of a+b in any units (1) being no greater than 3, each c has a value ranging from 1 to 2, each d has a value ranging from 0 to 2 and Z is a divalent hydrocarbon radical of from 2 to 18 inclusive carbon atoms, Z being free of aliphatic unsaturation, there being in each molecule of the ultimate siloxane composition units of (1) and (2) such that there is an average of from 1.3 to 2 R groups per silicon atom and that there are at least seven units of (2) per molecule.
Weyenberg in U.S. Pat. No. 3,175,993 discloses a composition consisting essentially of molecules of the average formula R.sub.y Si[(OSiR.sub.2).sub.x ZSiR.sub.3-a (OR').sub.a ].sub.4-y in which each R is free of aliphatic unsaturation and is selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals, and monovalent cyanoalkyl radicals all of 1 to 18 inclusive carbon atoms, Z is a divalent hydrocarbon radical free of aliphatic unsaturation of from 2 to 18 inclusive carbon atoms, R' is selected from the group consisting of haloalkyl radicals having no halogen alpha to the oxygen and alkyl radicals, both of less than 5 carbon atoms, y has an average value from 0 to 2 inclusive, x has a value of at least 3 and a has an average value from 2 to 3 inclusive.
Gignac in U.S. Pat. No. 3,509,081 discloses a cured elastomeric composition of matter obtained from a mixture of ingredients consisting essentially of (1) 100 parts of hydroxyl endblocked organopolysiloxane, (2) from 3 to 10 parts of a crosslinker selected from the group consisting of alkylpolysilicates, alkoxy silanes, and organosilicon compounds containing on the average at least three alkoxy radicals per molecule and at least two silicon atoms per molecule, at least some of the silicon atoms having hydrocarbon or halohydrocarbon radicals attached thereto, any remaining valences of the silicon atom being satisfied by substituents selected from the group consisting of oxygen atoms of SiOSi bonds, OH groups, and other silicon atoms, (3) from 0.1 part to 10 parts of a stannous salt of carboxylic acid, and (4) from 0.0002 to 0.005 part of a reducible azo-dye.
Alkoxy containing organopolysiloxanes have been disclosed in room temperature curable compositions and in moisture curable compositions. For example, Inoue et al., in U.S. Pat. No. 4,721,765 discloses a room temperature curable organopolysiloxane composition which comprises a hydroxyl or alkoxy terminated diorganopolysiloxane, a filler, an alkenyloxy silane, an organosilane or organopolysiloxane having at least one substituted or unsubstituted guanidino group, an amino containing organosilane, and an organic tin compound.
Homan in U.S. Pat. No. 4,743,474 discloses organopolysiloxane compositions which cure rapidly from the liquid to the non-liquid state when exposed to moisture which are used to rapidly coat a substrate. The organopolysiloxane compositions disclosed by Homan contain a large amount of a metal ester, such as tetraisopropyl titanate, dissolved in an organopolysiloxane fluid which contains moisture-reactive, silicon-bonded alkoxysilylorganic radicals.
Inoue in U.S. Pat. No. 5,049,635 discloses a room temperature curable organopolysiloxane composition which is capable of giving a cured silicone rubber having a low elastic modulus and low hardness and comprises (a) a silanol-terminated diorganopolysiloxane as the base component, (b) an organosilicon compound represented by the general formula R.sup.1 R.sup.2 Si(--OCMe.dbd.CHCOOR.sup.3).sub.2, in which Me is a methyl group, R.sup.1 is a methyl, vinyl, 3,3,3-trifluoropropyl or phenyl group, R.sup.2 is a group selected from the class consisting of methyl, vinyl, trimethyl siloxy, vinyl dimethyl siloxy, divinyl methyl siloxy, trivinyl siloxy, and 3,3,3-trifluoropropyl dimethyl siloxy groups and R.sup.3 is a methyl or ethyl group, (c) an organosilane or organosiloxane compound having, in a molecule, at least three groups selected from the class consisting of alkoxy groups, iminoxy groups, and alkenyloxy groups bonded to the silicon atom or atoms, and (d) an organosilane or organosiloxane compound having, in a molecule, at least one guanidino group represented by the formula (R.sup.4.sub.2 N).sub.2 C.dbd.N--, in which R.sup.4 is a hydrogen atom or a monovalent hydrocarbon group.
Chu et al. in U.S. Pat. No. 5,053,442 discloses a process for producing a silicone sealant which is stable in the absence of moisture, cures when exposed to moisture, has an elongation at break of greater than 800 percent, and has adhesion to concrete. The silicon sealant is produced by first mixing an alkoxysilethylene endblocked polymer, a dialkyldialkoxysilane, and a titanium catalyst, then mixing in precipitated calcium carbonate filler having a fatty acid surface treatment.
In contrast, the present invention relates to an alkoxy containing alkenyl functional organopolysiloxane anchorage additive and to its use in silicone coatings. Nowhere in the art is described the use of the silicone anchorage additives of the present invention to improve anchorage in curable silicone coating compositions.